Charles Ives

The last pope to take the name Benedict, before the one who made history this month announcing plans to retire, assumed his duties a few weeks after the outbreak of World War I. As Christmas 1914 approached, Benedict XV, who described the war as “the suicide of Europe,” pleaded for a Christmas truce. The military leaders refused, but somehow, at several points along the trenches, a surreal cease-fire broke out anyway. That short, peaceful spell inspired the 2005 film “Joyeux Noel,” which focused on the experiences of some Scottish, French and German troops on a battlefield in Belgium. That film, in turn, inspired “Silent Night,” an opera by Kevin Puts,...